A switching power supply detects a short circuit to ground, for example, by comparing a soft-start voltage Vss with a feedback voltage Vfb while securing an offset voltage ΔV. The switching power supply includes, for example, a short-circuit-to-ground detection circuit which detects a short circuit to ground at a monitoring target terminal. When a short circuit to ground occurs for the first time, the output of the short-circuit-to-ground detection circuit is masked for a first period. When a short circuit to ground occurs for the second or any succeeding time, the output of the short-circuit-to-ground detection circuit is masked for a second period shorter than the first period.